A Mo-based alloy is known as a material for use as a heat-resistant member particularly in a high-temperature environment, such as a friction stir welding tool, a glass melting jig tool, a high-temperature industrial furnace member, a hot extrusion die, a seamless tube manufacturing piercer plug, an injection molding hot runner nozzle, a casting insert mold, a resistance heating deposition container, an airplane jet engine, or a rocket engine.
In order to improve mechanical properties and oxidation resistance at a high temperature, various compounds or the like are added to Mo to thereby obtain Mo-based alloys.
There is known as such an additive a Mo—Si—B-based alloy such as Mo5SiB2. The properties of the alloy are quite important as a material that largely affects the properties of the heat-resistant member.
Herein, conventionally, the control of the properties of the Mo—Si—B-based alloy has been carried out by selecting/improving a raw material powder, a sintering method, and so on.
For example, in Patent Document 1, a Mo alloy containing a Mo—Si—B-based alloy is manufactured by mechanically alloying a Mo powder, a Si powder, and a B powder to produce a mixed powder and then compacting and heat-treating the obtained mixed powder (Patent Document 1).
Patent Documents 2 and 3 disclose a technique that manufactures a Mo—Si—B-based alloy by melting and rapidly solidifying raw materials and disperses the alloy in a body-centered cubic Mo matrix, thereby forming a material having a 0.2% proof stress of 100 MPa or more at 1300° C. (Patent Documents 2 and 3).
Further, in Patent Document 4, a Mo—Si—B alloy is formed by a plasma spraying method, wherein Mo, Si, and B are constituent elements and a Mo3Si phase, a Mo5Si3 phase, and a Mo5SiB2 phase coexist (Patent Document 4).
The Mo—Si—B-based alloys are manufactured by various methods as described above and are used for friction stir welding components as described in, for example, Patent Document 5 (Patent Document 5).